SULFOCONJUGATED AND FREE PLASMA-CATECHOLAMINE LEVELS AT REST AND DURING EXERCISE IN PATIENTS WITH IDIOPATHIC DILATED CARDIOMYOPATHY

Plasma levels of sulfoconjugated (sc) catecholamines (CA) have been sh own to be increased with activation of the sympathoadrenal system in a number of clinical settings. We evaluated the relation between scCA a nd clinical or hemodynamic parameters of patients with idiopathic dila ted cardiomyopathy (IDC) at rest and during incremental exercise testi ng. Eleven healthy subjects, nine patients in New York Heart Associati on (NYHA) functional class I (IDC-A group) and 11 in NYHA functional c lass II and III (IDC-B group) performed a symptom-limited, graded bicy cle exercise test. Resting, peak and various postexercise levels of pl asma free and scCA were determined by high-pressure liquid chromoatogr aphy. Resting CA levels obtained in the supine position were remarkabl e for elevations of free norepinephrine (NE) in IDC-B patients (355 +/ - 157 ng/l) as compared to IDC-A patients (177 +/- 54, p = 0.006) or h ealthy controls (193 +/- 74, p = 0.007). Similarly, scNE was highest i n IDC-B patients with 1856 +/- 1089 ng/l, followed by IDC-A (1028 +/- 187, p = 0.025) and control subjects (1109 +/- 440, p = 0.025). There was a highly significant correlation between free and scNE (r = 0.76, p < 0.0005). Whereas resting free dopamine (DA) levels were comparable in all three groups, scDA was found to be elevated clearly in IDC-B p atients (8772 +/- 2097 ng/l) and significantly different to IDC-A (578 6 +/- 2481, p = 0.01) or control subjects (4892 +/- 1575, p = 0.0005). The NYHA functional class and maximum exercise performance correlated best with resting scDA (r = 0.68, p = 0.001 and r = 0.56, p = 0.005, respectively). At peak exercixe, IDC-B patients exhibited a significan t decrease in scNE and sc epinephrine (E) (from 1856 +/- 1089 to 1495 +/- 932 ng/l, p < 0.005 and from 491 +/- 173 to 282 +/- 143 ng/l, p < 0.01) compared to controls (from 1109 +/- 444 to 1094 +/- 548 ng/l and from 379 +/- 200 to 329 +/- 134 ng/l). In IDC-B patients this decreas e in scNE and scE at peak exercise was related inversely to the rise i n free NE and E (r = -0.81, p < 0.005 and r = -0.68, p < 0.05). Restin g hemodynamic indices generally were reflected better by some free CA rather than by conjugated forms or by parameters of clinical performan ce. These findings suggest that in addition to free or scNE levels, re sting scDA is elevated in symptomatic patients with IDC. In the presen t study, scDA proved to be a more sensitive marker of heart failure th an resting free NE. Maximum exercise performance in symptomatic patien ts with IDC was accompanied by decreases in scNE and scE that were cor related to the degree of elevation of their respective free fractions.